Electrical signaling system.



B. F. GARDNER.

ELECTRICAL SIGNALING SYSTEM.

APPLI CATION FILED JAN. 18, 19MB.

Patented July 10, 1917.

specification.

BENJAMIN FULTON GMRDNER, OF. CHICAGO, ILLINOIS, ASSIGNOR OF ONE-HALF TO SEYMOUR STEDMAN, OF CHICAGO, ILLINOIS.

ELncrnIcAL srennnme srs'rnm.

Specification of Iletters'Patcnt.

, Patented July lo, 1am.

Application filed January 18, 1916. Serial No. 72,737.

To all whom it may concern:

Be it known that I, BENJAMIN FULTON GARDNER, a vcitizen of the United States, residing at Chicago, inthe county of Cook and State of Illinois, have invented new and useful Improvements in Electrical Signaling Systems, ofwhich the following is a My invention relates to improvements in electrical signaling systems. More particularly the invention is concerned with a means for energizing such systems from a three-wire distribution line having its neutral wire grounded as is common in centralstation supply systems. The type of apparatus to be employed is preferably the same as that illustrated and described in my companion application, Serial No. 69,568, filed Dec. 31, 1915, for a means for energizing electrical signaling systems. The present invention is concerned with the operation of an apparatus of the general type of my companion application when used in connection with the three-wire system referred to, it being my object to provide an arrangement by which the signaling circuit may be operated at the predetermined voltage and by no possibility may this voltage be exceeded, either between the two sides of the signaling system itself, or between either side of the same and the ground, and whether the main-line circuit or the signaling circuit be open or closed.

In short it is my object to so arrange the apparatus that although itbe energized by direct connection with arelatively high voltage service line, or main-line, the signali-ng circuit will be in all respects as safe both as to-life and fire hazard as though it were energized from a battery or dynamo of the proper low potential.

With this object in view I have provided I the arrangement illustrated diagrammatically by the accompanying drawing, in-

which Figure 1 is a diagrammatic view of a preferred form of apparatus embodying the in vention; Fig. 2 is a schematic diagram illustrating one modified circuit arrangement, and Fig. 3 is a schematic diagram illustratin a second modified circuit arrangement.

n the drawing, the numeral 1 (Fig. 1)

designates the two main-line wires "of a three-wire distribution system, and the numeral 2 designates the neutral or third wire this ty of the system, which will, in common pract ce, be groundedat one end as at 3, and split up 1nto a plurality of distribution lines each parallel ng one of the main-line wires, the system being thus divided into two parts w1th the current-consuming devices,'designated 4, designed to approximately balance one another, as'is well understood.

To apply my signal-energizing device to e of clrcuit, I preferably provide a two-po e electromagnetic switch or relay designated 5, and arranged to open or close simultaneously the mam-line wire 1 and neutral wire 2, through a resistance comprisingmembers 6, 6,-arranged in series, the latter being preferably composed of two or more conductors in parallel with one another, as shown in Fig. 1, the purpose bemg that if one of the members 6' should fail, the other will prevent the circuit from openmg at this point.

For energizing the coils" of the relay to cause it to thus open and close the circuit through the resistances 6, 6, I provide an independent battery circuit designated 7 and having a battery 8 anda suitable control switch or button 9 therein. Since the sole function of the battery circuit is to operate the relay, the battery may obviously.

10 and shown as having a bell 11 and telephone hook 12 therein. The signal shunt circuit 10 is designed to be constantly closed,

except in so far as it may be opened by the operation of the signaling devices themselves. The potentialdiflerence or voltage of the signal shunt will be predetermined by the main-line voltage and the relative resistances of the members 6 and 6. Thus the main-line may be a 220 volt system, giving 110 voltsfrom each of its sides to the neutral wire. Witha current of 1 am ere the resistances 6 and 6 may be adjusted in value so that there will be an 80 volt drop in the resistance 6 and a 30 volt drop in the resistance 6, which latter will then be the impressed E. M. F. for the signal shunt 10.

In operation the relay will normally V maintain the main linewire 1 and neutral wire 2 0 en, so that there will be no possibility 0 any current flow ng through the apparatus, and the signal line Wlll of course be wholly dead, both as between its two sides and between 'either side and. the ground. When the switch 9 of the control circuit is closed, the relay will be actuated to simultaneously close the l nes 1 and 2 through the resistance 6, 6. The drop of potential between the ends of the resistance 6' will thereupon energize the shunt 1 0 and the signaling devices therein, establishing .the predetermined potential differenceon 15 the two sides thereof. Since the resistance 6 is connected directly to the neutral or round wire 2, there will be no potential difference between ground and one slde of the signal shunt, while between the other side and ground only the predetermined 30 volt difference will exist. The shunt signal circuit therefor may be wired and protected according to the requirements of its limited voltage only and in the same manner as systems of like voltage energized from batter installations. v

hile I have shown a double-pole electromagnetic switch for opening both the line wire 1 and neutral wire 2, it will be understood that the neutral wire switch may be dispensed with without interfering withor changing the normal operation of the device, the double-pole switch being preferred however as a measure of additional security.

In Fig. 2 I have illustrated one such modification, in which the main-line wires.

" 21 and neutral 22 are arranged in the same fashion as in Fig. 1. The resistances 26, 26' are connected between one of the main-line wires and the neutral wire as shown, and the signal circuit 30 is shunted around the recuit in this figure, showing only a simple sistance 26. I have omitted the battery cirswitch 25 for opening and closing the mainline wire 21, the neutral wire being kept constantly connected with the resistance 26,

cally operated from independent circuits, as

in Fig. 1.

The mechanical constructlon and arrangement of the arts illustrated by the diagrammatic rawing accompanying this specification may be the same as that shown and described in my co-pending application heretofore referred to.

It should be understood that the structure described by this specification is illustrative only and for the purpose of making my invention more clear, and that I do not regard the invention as limited to any of the particularities of construction chosen for purposes of illustration, except in so far as I have included such limitations within the terms of the following claims.

What I claim is:

1. The combination with a three wire distribution system having its neutral wire grounded, of a resistance member interposed etween the neutral wire and one of the main-line wires of such system, a signal shunt-circuit having one end connected to said neutral wire and its other end connected to said resistance intermediate the length of the latter, signaling devices in the said signaling circuit, and means for opening and closing the main line wire ahead of the point of connection of said signal shunt with the said resistance.

2. The combination with a three wire distribution system having. its neutral wire grounded, of a resistance member interposed between the neutral, wire and one of the main-line wires of such system, a si al shunt-circuit having one end connecte to said neutral wire and its other end connected to said resistance intermediate the length of the latter, signaling devices in the said signaling circuit, a relay for opening and closing the main-line wire ahead of the point of connection of said signal shunt with the said resistance, and an independent circuit for energizing the said relay.

3. The combination with a three wire distribution system having its neutral Wire grounded, of a resistance member interposed between the neutral wire and one of the main-line wires of' such system, a signalshunt circuit having one end connected to said neutral wire and its other end connected to said resistance intermediate the length of the latter, signaling devices in said signal- 1ng circuit, a double-pole relay for opening and closing said main-line .and neutral wires, and an independent circuit for energizing said relay.

BENJAMIN FULTON GARDNER.

In presence of:

D. C. THORSEN, K. ONEILL. 

